Leader of the Flock

Training endangered cranes to follow a man in an ultralight means risks as well as rewards

08-01-1998
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Les Line

Ultralight-aircraft enthusiast Kent Clegg and a contingent of young sandhill and whooping cranes were riding a thermal over a Colorado plateau last October when a golden eagle, drifting at 10,000 feet on the same bubble of hot air, folded its wings, homed in on one of the cranes like a missile--and missed!

Clegg is an independent wildlife biologist who has worked with cranes for 20 years and has a dream of using ultralights to start a whooping crane flock in the Rocky Mountain area. This was his third trip leading a flock of cranes on an experimental migration from his ranch in Grace, Idaho, to Bosque del Apache National Wildlife Refuge in New Mexico. The 800-mile route follows the spine of the southern Rocky Mountains before crossing roadless canyon lands--all prime golden eagle country--and attacks on his charges were nothing new. The day before, one of the powerful raptors had smashed a whooper to the ground, ripping a bloody wound in a drumstick, before being scared off by Clegg´s support team. Stitched up by a veterinarian and dosed with antibiotics, the crane finished its journey in a trailer.

But this time, with the eagle circling for another try, it was Clegg who had a close call. He had trained the crane chicks to think of him as their parent from the day they hatched at Patuxent Wildlife Research Center in Maryland. And as the birds jostled to get close to the plane for safety, a sandhill became snagged on the emergency parachute canister. To keep the bird from going through the rear-mounted propeller, Clegg cut the throttle, nosed the plane downward and landed in a hay field with his panicked flock close behind.

"What Kent did was extremely dangerous," says biologist Tom Stehn of Aransas National Wildlife Refuge on the Texas coast, who watched the flight with the ground crew. It wasn´t the only near-accident during the 1997 migration lesson. Errol Spaulding, pilot of the second ultralight on the nine-day trip to Bosque del Apache, was chasing an eagle away from the cranes when his engine quit during a sharp turn because of a fuel problem. Spaulding was only 200 feet from the ground and barely had time to level out and find a flat spot to land, stopping at the brink of a gully.

Those incidents, together with another crane-ultralight entanglement in Canada that wrecked the plane and injured its pilot, add safety concerns to a list of scientific, logistical and political questions about the popular idea of using the fragile aircraft to start a new migratory whooper flock. "I´m not convinced we should push full-bore forward with the ultralight plan," says Stehn, who is the U.S. Fish and Wildlife Service coordinator of the international Whooping Crane Recovery Team. Still, for now ultralights remain part of a grand plan to ensure the species´ survival.

The whooping crane may be the most famous bird on the North American if not the worldwide list of rare wildlife, and the recovery team´s goal is to upgrade the species´ official status from endangered to threatened by the year 2020. At the historic low point in 1942, only 16 whoopers returned to their winter home at the Aransas refuge from their then-unknown breeding grounds in the muskeg wilderness of northern Canada´s Wood Buffalo National Park. Last winter a record 182 whooping cranes, including an all-time high count of 30 juveniles, arrived in Texas. Despite those heartening numbers, the species remains at considerable risk. As Stehn points out, the Aransas marshes lie along a crowded shipping lane for petroleum and chemicals. A spill could devastate the habitat and kill dozens of cranes.

The recovery team´s plan, then, calls for supplementing the Aransas-Wood Buffalo whoopers with two other self-sustaining populations, each with at least 25 breeding pairs. One would be a nonmigratory flock on the pasturelands of central Florida, where dozens of captive-raised cranes have been released over the past seven years, although none have mated and produced young. Cranes living in the South where there is a year-round food supply have no need to migrate, and there was a sedentary flock of whoopers in Louisiana until it was devastated by a hurricane in 1940.

A new migratory flock, meanwhile, would nest and winter at locations well east of the historic flight corridor between Texas and the Canadian province of Manitoba so there would be no commingling of the two populations. And therein lies a big problem as well as the potential role of ultralight aircraft, because whooping cranes, unlike many small birds, need to be shown the way home.

While the phenomenon defies full scientific understanding, biologists know that songbirds like orioles and warblers, as well as plovers and other shorebirds, are genetically programmed to use celestial and magnetic cues to navigate at night between their breeding and wintering grounds. Young of the year of those species, moreover, migrate thousands of miles without help of any kind from their parents.

Among waterfowl and wading birds like cranes, however, the migration map is handed down from one generation to the next. Young geese, swans and cranes move out in autumn with their parents, flying by day and apparently memorizing the landscape from a bird´s-eye view as well as picking up other cues. The family group typically spends the winter together and returns to its nesting grounds the following spring.

The challenge this method poses is huge. First, how can juvenile whoopers be taught to migrate if they are raised by humans in a place where there are no adult cranes to lead them south? Second, will the inexperienced birds make it through the winter without parents to teach them survival skills? And the $64,000 question: Will they find their way back to the northern marshes and then help lead a new batch of whoopers to the wintering grounds?

Two decades ago, biologists thought they had all the answers. They used a technique called cross-fostering in an attempt to launch a whooping crane flock at Grays Lake National Wildlife Refuge in Idaho. Over 14 years, workers collected 289 whooper eggs from the Canadian nesting grounds and the captive-breeding facility at Patuxent, placing them in sandhill crane nests at Grays Lake. (The sandhill is the most abundant of the world´s 15 crane species, with a population estimated at a half-million birds.)

As expected, the juvenile whoopers followed their foster parents to the Bosque del Apache refuge, a famous sandhill wintering place, and returned with them to Idaho in the spring. The flaw in the scheme was the refusal of the Grays Lake whoopers to mate with their own species. They were sexually imprinted on the sandhills and the only offspring produced was a single hybrid.

Ironically, imprinting whooper chicks on a foster parent--a human one this time--may still be the recovery team´s best hope. The idea of using an ultralight as a surrogate flock leader gained momentum in 1993, when Canadian wildlife sculptor Bill Lishman guided Canada geese from his airstrip near Toronto to a waterfowl sanctuary in Virginia. Lishman adapted techniques that Austrian ethologist Konrad Lorenz pioneered with greylag geese in the 1930s: He conditioned the goslings to the sounds of his voice and the aircraft´s engine while they were hatching and trained them to run and eventually fly behind his 250-pound plane. Most of those geese, wearing identifying neck bands, returned to Lishman´s doorstep in the spring. Lishman successfully repeated the experiment in 1994 with a flight to South Carolina, a feat fictionalized in the Hollywood movie Fly Away Home.

While Lishman, his pilot-partner Joe Duff and their geese students performed for cameras in the summer of 1995, Kent Clegg was exercising his first class of sandhill cranes behind an all-terrain vehicle and an ultralight painted to look something like a crane. Clegg´s aircraft, called a Dragonfly because of large "flapperons" that give it extra lift, is designed to climb to 15,000 feet and handle mountain air turbulence.

However, leading a flock of cranes on migration is not the same as flying with geese. While the honkers flap along in formation, cranes instead behave like gliders, using thermals to gain altitude. Then they soar long distances in leisurely fashion, finding more thermals when they need to ascend again. But a crane´s energy is quickly sapped when it has to continuously flap its long wings (the bird´s wingspan measures more than 7 feet) behind a slow-flying ultralight, and some birds on Clegg´s Idaho-to-New Mexico flights have virtually dropped out of the sky in exhaustion.

Also, a crane is about twice the size of a goose and a greater threat to pilot and plane if the bird gets mixed up with an ultralight´s open-cockpit structure. Duff was lucky to escape with only a dislocated shoulder last fall on a trial flight when a sandhill caught its feet in the wires of his aircraft and he crashed in the top of an oak.

Yet Lishman says, "In some ways, cranes are easier to work with than geese because they fly higher and faster, up to 40 miles an hour. We´ve had goose flocks that persisted in flying at treetop level, which is dangerous since you don´t have much time to pick a soft tree to land on."

Ultralight pilots also have to contend with nature´s whims. A "good day," according to Clegg, is one that covers 90 miles in two legs during the early morning and late afternoon hours when flight conditions are best. Last fall, however, Lishman and Duff led seven sandhills from Ontario to Virginia, and the 540-mile trip took 22 days because of interminable rains. "We spent most of the time sitting on the ground, looking at the sky and waiting for it to open up a bit," says Lishman. "A crane could almost fly that distance in a day." Still, in early April the work paid off as six of the sandhills found their way back to Ontario on their own.

Consider, however, the fact that a migration route from the recovery team´s proposed whooping crane release site in Manitoba to a winter home in Louisiana or Florida could be as long as 1,800 miles. "A lot of people are sold on the ultralight idea," says biologist Brian Johns, the team´s Canadian Wildlife Service coordinator. "I´ve tried to tell them that it´s not as easy as it looks. It´s not the same as flying in a 747 at 35,000 feet."

Clegg, whose work has been partially funded by the U.S. Fish and Wildlife Service, agrees. The first and only pilot to lead whooping cranes in flight, he thinks the Rocky Mountain area is still the best place to establish another whooper flock. "Our flyway is a short one, and we know every inch of the route," he says.

But Clegg, his Dragonfly and his dream have been effectively grounded, at least for now, by the international recovery team´s decision to use the eastern route. Lishman´s Ontario-based team will attempt a sandhill crane migration from Manitoba to the Gulf Coast this fall as a prelude, everyone hopes, to a flight with whoopers in a year or two.

Why Manitoba? Mainly because the Canadian Wildlife Service is eager to attempt a reintroduction north of the border. After all, most of the eggs for the Grays Lake experiment in Idaho came from Canada, where the wild flock spends half the year. Former whooper breeding places in the western prairie provinces were rejected as release sites because the marshes are subject to outbreaks of avian botulism or because sandhill cranes in those areas migrate to Texas and young whoopers might follow.

The most promising Canadian reintroduction site, Johns says, is between Lake Manitoba and Lake Winnipeg in south-central Manitoba near the town of Ashern. Whoopers nested in that area in the 1800s, a time when their principal breeding range followed a swath of grasslands from Illinois to Alberta and there may have been as many as 700 nesting pairs on the unbroken prairie.

Meanwhile, the recovery team´s search for a new whooper wintering place has been narrowed to two locations: Marsh Island Wildlife Refuge, a state-owned preserve on the Louisiana coast; and Chassahowitzka National Wildlife Refuge, which lies north of Clearwater on Florida´s west coast. The habitat at both locations resembles the Aransas refuge, with large expanses of salt marsh and an abundance of blue crabs, the whooping crane´s favorite winter food.

The recovery team will finalize its plans at a late-summer meeting. But Stehn cautions that opposition from state game and fish departments could block the Manitoba project since waterfowl hunting areas would have to be closed to shooting while the majestic white birds are passing through. The U.S. Fish and Wildlife Service is concerned that hunters might confuse the whoopers with snow geese, which also are big and white with black wingtips. "If the states are negative, it´s not going to happen," Stehn says.

It´s clear that efforts to assure the whooping crane´s survival far into the new millenium have only just begun. If the ultralight plan crashes, for example, could a remote-controlled, larger-than-life flying model of a crane be used instead? Could young whoopers be trucked along the migration route and let out to fly every 50 miles to learn the lay of the land? Both ideas are waiting in the wings.

Stay tuned for the next episode.

Field Editor Les Line has watched cranes on four continents, including whoopers in Texas.